Elastic substantially linear olefin polymers

ABSTRACT

Substantially linear olefin polymers having a melt flow ratio, I 10  /I 2 , ≧5.63, a molecular weight distribution, M w  /M n , defined by the equation: M w  /M n  ≦(I 10  /I 2 )-4.63, and a critical shear stress at onset of gross melt fracture of greater than about 4×10 6  dyne/cm 2  and their method of manufacture are disclosed. The substantially linear olefin polymers preferably have at least about 0.01 long chain branches/1000 carbons and a molecular weight distribution from about 1.5 to about 2.5. The new polymers have improved processability over conventional olefin polymers and are useful in producing fabricated articles such as fibers, films, and molded parts.

FIELD OF THE INVENTION

This invention relates to elastic substantially linear olefin polymershaving improved processability, e.g., low susceptibility to meltfracture, even under high shear stress extrusion conditions. Methods ofmanufacturing these polymers are also disclosed.

BACKGROUND OF THE INVENTION

Molecular weight distribution (MWD), or polydispersity, is a well knownvariable in polymers. The molecular weight distribution, sometimesdescribed as the ratio of weight average molecular weight (M_(w)) tonumber average molecular weight (M_(n)) (i.e., M_(w) /M_(n)) can bemeasured directly, e.g., by gel permeation chromatography techniques, ormore routinely, by measuring I₁₀ /I₂ ratio, as described in ASTM D-1238.For linear polyolefins, especially linear polyethylene, it is well knownthat as M_(w) /M_(n) increases, I₁₀ /I₂ also increases.

John Dealy in "Melt Rheology and Its Role in Plastics Processing" (VanNostrand Reinhold, 1990) page 597 discloses that ASTM D-1238 is employedwith different loads in order to obtain an estimate of the shear ratedependence of melt viscosity, which is sensitive to weight averagemolecular weight (M_(w)) and number average molecular weight (M_(n)).

Bersted in Journal of Applied Polymer Science Vol. 19, page 2167-2177(1975) theorized the relationship between molecular weight distributionand steady shear melt viscosity for linear polymer systems. He alsoshowed that the broader MWD material exhibits a higher shear rate orshear stress dependency.

Ramamurthy in Journal of Rheology, 30(2), 337-357 (1986), and Moynihan,Baird And Ramanathan in Journal of Non-Newtonian Fluid Mechanics, 36,255-263 (1990), both disclose that the onset of sharkskin (i.e., meltfracture) for linear low density polyethylene (LLDPE) occurs at anapparent shear stress of 1-1.4×10⁶ dyne/cm², which was observed to becoincident with the change in slope of the flow curve. Ramamurthy alsodiscloses that the onset of surface melt fracture or of gross meltfracture for high pressure low density polyethylene (HP-LDPE) occurs atan apparent shear stress of about 0.13 MPa (1.3×10⁶ dynes/cm²).

Kalika and Denn in Journal of Rheology, 31, 815-834 (1987) confirmed thesurface defects or sharkskin phenomena for LLDPE, but the results oftheir work determined a critical shear stress of 2.3×10⁶ dyne/cm²,significantly higher than that found by Ramamurthy and Moynihan et al.

International Patent Application (Publication No. WO 90/03414) publishedApr. 5, 1990, discloses linear ethylene interpolymer blends with narrowmolecular weight distribution and narrow short chain branchingdistributions (SCBDS). The melt processibility of the interpolymerblends is controlled by blending different molecular weightinterpolymers having different narrow molecular weight distributions anddifferent SCBDs.

Exxon Chemical Company, in the Preprints of Polyolefins VIIInternational Conference, page 45-66, Feb. 24-27 1991, disclose that thenarrow molecular weight distribution (NMWD) resins produced by theirEXXPOL™ technology have higher melt viscosity and lower melt strengththan conventional Ziegler resins at the same melt index. In a recentpublication, Exxon Chemical Company has also taught that NMWD polymersmade using a single site catalyst create the potential for melt fracture("New Specialty Linear Polymers (SLP) For Power Cables," by MonicaHendewerk and Lawrence Spenadel, presented at IEEE meeting in Dallas,Tex., September, 1991).

Previously known narrow molecular weight distribution linear polymersdisadvantageously possessed low shear sensitivity or low I₁₀ /I₂ value,which limits the extrudability of such polymers. Additionally, suchpolymers possessed low melt elasticity, causing problems in meltfabrication such as film forming processes or blow molding processes(e.g., sustaining a bubble in the blown film process, or sag in the blowmolding process etc.). Finally, such resins also experienced meltfracture surface properties at relatively low extrusion rates therebyprocessing unacceptably.

SUMMARY OF THE INVENTION

We have now discovered a new family of substantially linear olefinpolymers which have many improved properties and a method of theirmanufacture. The substantially linear olefin polymers have (1) high meltelasticity and, (2) relatively narrow molecular weight distributionswith exceptionally good processibility while maintaining good mechanicalproperties and (3) they do not melt fracture over a broad range of shearstress conditions. These properties are obtained without benefit ofspecific processing additives. The new polymers can be successfullyprepared in a continuous polymerization process using constrainedgeometry catalyst technology, especially when polymerized utilizingsolution process technology.

The improved properties of the polymers include improved melt elasticityand processability in thermal forming processes such as extrusion,blowing film, injection molding and blowmolding.

Substantially linear polymers made according to the present inventionhave the following novel properties:

a) a melt flow ratio, I₁₀ /I₂, ≧5.63,

b) a molecular weight distribution, M_(w) /M_(n), defined by theequation:

    M.sub.w /M.sub.n ≦(I.sub.10 /I.sub.2)-4.63, and

c) a critical shear stress at onset of gross melt fracture of greaterthan about 4×10⁶ dyne/cm².

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation of a polymerization processsuitable for making the polymers of the present invention.

FIG. 2 plots data describing the relationship between I₁₀ /I₂ and M_(w)/M_(n) for polymer Examples 5 and 6 of the invention, and fromcomparative examples 7-9.

FIG. 3 plots the shear stress versus shear rate for Example 5 andcomparative example 7, described herein.

FIG. 4 plots the shear stress versus shear rate for Example 6 andcomparative example 9, described herein.

FIG. 5 plots the heat seal strength versus heat seal temperature of filmmade from Examples 10 and 12, and comparative examples 11 and 13,described herein.

DETAILED DESCRIPTION OF THE INVENTION

Other properties of the substantially linear polymers include:

a) a density from about 0.85 grams/cubic centimeter (g/cc) to about 0.97g/cc (tested in accordance with ASTM D-792), and

b) a melt index, MI, from about 0.01 grams/10 minutes to about 1000gram/10 minutes.

Preferably the melt flow ratio, I₁₀ /I₂, is from about 7 to about 20.

The molecular weight distribution (i.e., M_(w) /M_(n)) is preferablyless than about 5, especially less than about 3.5, and most preferablyfrom about 1.5 to about 2.5.

Throughout this disclosure, "melt index" or "I₂ " is measured inaccordance with ASTM D-1238 (190/2.16); "I₁₀ " is measured in accordancewith ASTM D-1238 (190/10).

The melt tension of these new polymers is also surprisingly good, e.g.,as high as about 2 grams or more, especially for polymers which have avery narrow molecular weight distribution (i.e., M_(w) /M_(n) from about1.5 to about 2.5).

The substantially linear polymers of the present invention can behomopolymers of C₂ -C₂₀ olefins, such as ethylene, propylene,4-methyl-1-pentene, etc., or they can be interpolymers of ethylene withat least one C₃ -C₂₀ α-olefin and/or C₂ -C₂₀ acetylenically unsaturatedmonomer and/or C₄ -C₁₈ diolefins. The substantially linear polymers ofthe present invention can also be interpolymers of ethylene with atleast one of the above C₃ -C₂₀ α-olefins, diolefins and/oracetylenically unsaturated monomers in combination with otherunsaturated monomers.

Monomers usefully polymerized according to the present inventioninclude, for example, ethylenically unsaturated monomers, acetyleniccompounds, conjugated or nonconjugated dienes, polyenes, carbonmonoxide, etc. Preferred monomers include the C₂₋₁₀ α-olefins especiallyethylene, propylene, isobutylene, 1-butene, 1-hexene,4-methyl-1-pentene, and 1-octene. Other preferred monomers includestyrene, halo- or alkyl substituted styrenes, tetrafluoroethylene,vinylbenzocyclobutane, 1,4-hexadiene, and naphthenics (e.g.,cyclo-pentene, cyclo-hexene and cyclo-octene).

The term "substantially linear" polymers means that the polymer backboneis either unsubstituted or substituted with up to 3 long chainbranches/1000 carbons. Preferred polymers are substituted with about0.01 long chain branches/1000 carbons to about 3 long chainbranches/1000 carbons, more preferably from about 0.01 long chainbranches/1000 carbons to about 1 long chain branches/1000 carbons, andespecially from about 0.3 long chain branches/1000 carbons to about 1long chain branches/1000 carbons.

Long chain branching is defined herein as a chain length of at leastabout 6 carbons, above which the length cannot be distinguished using ¹³C nuclear magnetic resonance spectroscopy. The long chain branch can beas long as about the same length as the length of the polymer back-bone.

Long chain branching is determined by using ¹³ C nuclear magneticresonance (NMR) spectroscopy and is quantified using the method ofRandall (Rev. Macromol. Chem. Phys., C29 (2&3), p. 285-297), thedisclosure of which is incorporated herein by reference.

"Melt tension" is measured by a specially designed pulley transducer inconjunction with the melt indexer. Melt tension is the load that theextrudate or filament exerts while passing over the pulley at thestandard speed of 30 rpm. The melt tension measurement is similar to the"Melt Tension Tester" made by Toyoseiki and is described by John Dealyin "Rheometers for Molten Plastics", published by Van Nostrand ReinholdCo. (1982) on page 250-251.

The "rheological processing index" (PI) is the apparent viscosity (inkpoise) of a polymer measured by a gas extrusion rheometer (GER). Thegas extrusion rheometer is described by M. Shida, R. N. Shroff and L. V.Cancio in Polymer Engineering Science, Vol. 17, no. 11, p. 770 (1977),and in "Rheometers for Molten Plastics" by John Dealy, published by VanNostrand Reinhold Co. (1982) on page 97, both publications of which areincorporated by reference herein in their entirety. All GER experimentsare performed at a temperature of 190° C., at nitrogen pressures between5250 to 500 psig using a 0.0296 inch diameter, 20:1 L/D die. An apparentshear stress vs. apparent shear rate plot is used to identify the meltfracture phenomena. According to Ramamurthy in Journal of Rheology,30(2), 337-357, 1986, above a certain critical flow rate, the observedextrudate irregularities may be broadly classified into two main types:surface melt fracture and gross melt fracture.

Surface melt fracture occurs under apparently steady flow conditions andranges in detail from loss of specular gloss to the more severe form of"sharkskin". Gross melt fracture occurs at unsteady flow conditions andranges in detail from regular (alternating rough and smooth, helical,etc.) to random distortions. For commercial acceptability, (e.g., inblown film products), surface defects should be minimal, if not absent.The critical shear rate at onset of surface melt fracture (OSMF) andonset of gross melt fracture (OGMF) will be used herein based on thechanges of surface roughness and configurations of the extrudatesextruded by a GER. Preferably, the critical shear stress at the OGMF andthe critical shear stress at the OSMF for the substantially linearethylene polymers described herein is greater than about 4×10⁶ dyne/cm²and greater than about 2.8×10⁶ dyne/cm², respectively.

For the polymers described herein, the PI is the apparent viscosity (inKpoise) of a material measured by GER at a temperature of 190° C., atnitrogen pressure of 2500 psig using a 0.0296 inch diameter, 20:1 L/Ddie, or corresponding apparent shear stress of 2.15×10⁶ dyne/cm². Thenovel polymers described herein preferably have a PI in the range ofabout 0.01 kpoise to about 50 kpoise, preferably about 15 kpoise orless.

The SCBDI (Short Chain Branch Distribution Index) or CDBI (CompositionDistribution Branch Index) is defined as the weight percent of thepolymer molecules having a comonomer content within 50 percent of themedian total molar comonomer content. The CDBI of an polymer is readilycalculated from data obtained from techniques known in the art, such as,for example, temperature rising elution fractionation (abbreviatedherein as "TREF") as described, for example, in Wild et al, Journal ofPolymer Science, Poly. Phys. Ed., Vol. 20, p. 441 (1982), or in U.S.Pat. No. 4,798,081, both disclosures of which are incorporated herein byreference. The SCBDI or CDBI for the new polymers of the presentinvention is preferably greater than about 30 percent, especiallygreater than about 50 percent.

The most unique characteristic of the presently claimed polymers is ahighly unexpected flow property as shown in FIG. 2, where the I₁₀ /I₂value is essentially independent of polydispersity index (i.e. M_(w)/M_(n)). This is contrasted with conventional polyethylene resins havingrheological properties such that as the polydispersity index increases,the I₁₀ /I₂ value also increases. Measurement of the polydispersityindex is done according to the following technique:

The polymers are analyzed by gel permeation chromatography (GPC) on aWaters 150C high temperature chromatographic unit equipped with threelinear mixed bed columns (Polymer Laboratories (10 micron particlesize)), operating at a system temperature of 140° C. The solvent is1,2,4-trichlorobenzene, from which about 0.5% by weight solutions of thesamples are prepared for injection. The flow rate is 1.0milliliter/minute and the injection size is 100 microliters.

The molecular weight determination is deduced by using narrow molecularweight distribution polystyrene standards (from Polymer Laboratories) inconjunction with their elution volumes. The equivalent polyethylenemolecular weights are determined by using appropriate Mark-Houwinkcoefficients for polyethylene and polystyrene (as described by Williamsand Word in Journal of Polymer Science, Polymer Letters, Vol. 6,(621)1968, incorporated herein by reference) to derive the equation:

    M.sub.polyethylene =(a)(M.sub.polystyrene).sup.b

In this equation, a=0.4316 and b=1.0. Weight average molecular weight,M_(w), is calculated in the usual manner according to the formula:

    M.sub.w =(R)(w.sub.i)(M.sub.i)

where w_(i) and M_(i) are the weight fraction and molecular weightrespectively of the ith fraction eluting from the GPC column.

Another highly unexpected characteristic of the polymers of the presentinvention is their non-susceptibility to melt fracture or the formationof extrudate defects during high pressure, high speed extrusion.Preferably, polymers of the present invention do not experience"sharkskin" or surface melt fracture during the GER extrusion processeven at an extrusion pressure of 5000 psi and corresponding apparentstress of 4.3×10⁶ dyne/cm². In contrast, a conventional LLDPEexperiences "sharkskin" or onset of surface melt fracture (OSMF) at anapparent stress under comparable conditions as low as 1.0-1.4×10⁶dyne/cm².

Improvements of melt elasticity and processibility over conventionalLLDPE resins with similar MI are most pronounced when I₂ is lower thanabout 3 grams/10 minutes. Improvements of physical properties such asstrength properties, heat seal properties, and optical properties, overthe conventional LLDPE resins with similar MI, are most pronounced whenI₂ is lower than about 100 grams/10 minutes. The substantially linearpolymers of the present invention have processibility similar to that ofHigh Pressure LDPE while possessing strength and other physicalproperties similar to those of conventional LLDPE, without the benefitof special adhesion promoters (e.g., processing additives such as Viton™fluoroelastomers made by E. I. DuPont de Nemours & Company).

The improved melt elasticity and processibility of the substantiallylinear polymers according to the present invention result, it isbelieved, from their method of production. The polymers may be producedvia a continuous controlled polymerization process using at least onereactor, but can also be produced using multiple reactors (e.g., using amultiple reactor configuration as described in U.S. Pat. No. 3,914,342,incorporated herein by reference) at a polymerization temperature andpressure sufficient to produce the interpolymers having the desiredproperties. According to one embodiment of the present process, thepolymers are produced in a continuous process, as opposed to a batchprocess. Preferably, the polymerization temperature is from about 20° C.to about 250° C., using constrained geometry catalyst technology. If anarrow molecular weight distribution polymer (M_(w) /M_(n) of from about1.5 to about 2.5) having a higher I₁₀ /I₂ ratio (e.g. I₁₀ /I₂ of about 7or more, preferably at least about 8, especially at least about 9) isdesired, the ethylene concentration in the reactor is preferably notmore than about 8 percent by weight of the reactor contents, especiallynot more than about 4 percent by weight of the reactor contents.Preferably, the polymerization is performed in a solution polymerizationprocess. Generally, manipulation of I₁₀ /I₂ while holding M_(w) /M_(n)relatively low for producing the novel polymers described herein is afunction of reactor temperature and/or ethylene concentration. Reducedethylene concentration and higher temperature generally produces higherI₁₀ /I₂.

Suitable catalysts for use herein preferably include constrainedgeometry catalysts as disclosed in U.S. application Ser. Nos.: 545,403,filed Jul. 3, 1990; 758,654, filed Sep. 12, 1991; 758,660, filed Sep.12, 1991; and 720,041, filed Jun. 24, 1991, the teachings of all ofwhich are incorporated herein by reference.

The monocyclopentadienyl transition metal olefin polymerizationcatalysts taught in U.S. Pat. No. 5,026,798, the teachings of which areincorporated herein by reference, are also suitable for use in preparingthe polymers of the present invention.

The foregoing catalysts may be further described as comprising a metalcoordination complex comprising a metal of groups 3-10 or the Lanthanideseries of the Periodic Table of the Elements and a delocalized π-bondedmoiety substituted with a constrain-inducing moiety, said complex havinga constrained geometry about the metal atom such that the angle at themetal between the centroid of the delocalized, substituted π-bondedmoiety and the center of at least one remaining substituent is less thansuch angle in a similar complex containing a similar π-bonded moietylacking in such constrain-inducing substituent, and provided furtherthat for such complexes comprising more than one delocalized,substituted π-bonded moiety, only one thereof for each metal atom of thecomplex is a cyclic, delocalized, substituted π-bonded moiety. Thecatalyst further comprises an activating cocatalyst.

Preferred catalyst complexes correspond to the formula: ##STR1##wherein:

M is a metal of group 3-10, or the Lanthanide series of the PeriodicTable of the Elements;

Cp* is a cyclopentadienyl or substituted cyclopentadienyl group bound inan η⁵ bonding mode to M;

Z is a moiety comprising boron, or a member of group 14 of the PeriodicTable of the Elements, and optionally sulfur or oxygen, said moietyhaving up to 20 non-hydrogen atoms, and optionally Cp* and Z togetherform a fused ring system;

X independently each occurrence is an anionic ligand group or neutralLewis base ligand group having up to 30 non-hydrogen atoms;

n is 0, 1, 2, 3, or 4 and is 2 less than the valence of M; and

Y is an anionic or nonanionic ligand group bonded to Z and 51 comprisingnitrogen, phosphorus, oxygen or sulfur and having up to 20 non-hydrogenatoms, optionally Y and Z together form a fused ring system.

More preferably still, such complexes correspond to the formula:##STR2##

wherein R' each occurrence is independently selected from the groupconsisting of hydrogen, alkyl, aryl, silyl, germyl, cyano, halo andcombinations thereof having up to 20 non-hydrogen atoms;

X each occurrence independently is selected from the group consisting ofhydride, halo, alkyl, aryl, silyl, germyl, aryloxy, alkoxy, amide,siloxy, neutral Lewis base ligands and combinations thereof having up to20 non-hydrogen atoms;

Y is --O--, --S--, --NR*--, --PR*--, or a neutral two electron donorligand selected from the group consisting of OR*, SR*, NR*₂, or PR*₂ ;

M is a previously defined; and

Z is SiR*₂, CR*₂, SiR*₂ SiR*₂, CR*₂ CR*₂, CR*═CR*, CR*₂ SiR*₂, GeR*₂,BR*, BR*₂ ; wherein:

R* each occurrence is independently selected from the group consistingof hydrogen, alkyl, aryl, silyl, halogenated alkyl, halogenated arylgroups having up to 20 non-hydrogen atoms, and mixtures thereof, or twoor more R* groups from Y, Z, or both Y and Z form a fused ring system;and

n is 1 or 2.

It should be noted that whereas formula I and the following formulasindicate a cyclic structure for the catalysts, when Y is a neutral twoelectron donor ligand, the bond between M and Y is more accuratelyreferred to as a coordinate-covalent bond. Also, it should be noted thatthe complex may exist as a dimer or higher oligomer.

Further preferably, at least one of R', Z, or R* is an electron donatingmoiety. Thus, highly preferably Y is a nitrogen or phosphorus containinggroup corresponding to the formula --N(R"-- or --P(R")--, wherein R" isC₁₋₁₀ alkyl or aryl, i.e. an amido or phosphido group.

Most highly preferred complex compounds are amidosilane- oramidoalkanediyl- compounds corresponding to the formula: ##STR3##wherein:

M is titanium, zirconium or hafnium, bound in an η⁵ bonding mode to thecyclopentadienyl group;

R' each occurrence is independently selected from the group consistingof hydrogen, silyl, alkyl, aryl and combinations thereof having up to 10carbon or silicon atoms;

E is silicon or carbon;

X independently each occurrence is hydride, halo, alkyl, aryl, aryloxyor alkoxy of up to 10 carbons;

m is 1 or 2; and

n is 1 or 2.

Examples of the above most highly preferred metal coordination compoundsinclude compounds wherein the R' on the amido group is methyl, ethyl,propyl, butyl, pentyl, hexyl, (including isomers), norbornyl, benzyl,phenyl, etc.; the cyclopentadienyl group is cyclopentadienyl, indenyl,tetrahydroindenyl, fluorenyl, octahydrofluorenyl, etc.; R' on theforegoing cyclopentadienyl groups each occurrence is hydrogen, methyl,ethyl, propyl, butyl, pentyl, hexyl, (including isomers), norbornyl,benzyl, phenyl, etc.; and X is chloro, bromo, iodo, methyl, ethyl,propyl, butyl, pentyl, hexyl, (including isomers), norbornyl, benzyl,phenyl, etc. Specific compounds include:(tert-butylamido)(tetramethyl-η⁵-cyclopentadienyl)-1,2-ethanediylzirconium dichloride,(tert-butylamido)(tetra-methyl-η⁵-cyclopentadienyl)-1,2-ethanediyltitanium dichloride,(methylamido)(tetramethyl-η⁵ -cyclopentadienyl)-1,2-ethanediylzirconiumdichloride, (methylamido) (tetramethyl-η⁵-cycloperitadienyl)-1,2-ethanediyltitanium dichloride,(ethylamido)(tetramethyl-η⁵ -cyclopentadienyl)-methylenetitaniumdichloro, (tert-butylamido)dibenzyl(tetramethyl-η⁵ -cyclopentadienyl)silanezirconium dibenzyl, (benzylamido)dimethyl(tetramethyl-η⁵-cyclopentadienyl)silanetitanium dichloride,(phenylphosphido)dimethyl(tetramethyl-η⁵-cyclopentadienyl)silanezirconium dibenzyl,(tert-butylamido)dimethyl(tetramethyl-η⁵-cyclopentadienyl)silanetitanium dimethyl, and the like.

The complexes may be prepared by contacting a derivative of a metal, M,and a group I metal derivative or Grignard derivative of thecyclopentadienyl compound in a solvent and separating the saltbyproduct. Suitable solvents for use in preparing the metal complexesare aliphatic or aromatic liquids such as cyclohexane,methylcyclohexane, pentane, hexane, heptane, tetrahydrofuran, diethylether, benzene, toluene, xylene, ethylbenzene, etc., or mixturesthereof.

In a preferred embodiment, the metal compound is MX_(n+1), i.e. M is ina lower oxidation state than in the corresponding compound, MX_(n+2) andthe oxidation state of M in the desired final complex. A noninterferingoxidizing agent may thereafter be employed to raise the oxidation stateof the metal. The oxidation is accomplished merely by contacting thereactants utilizing solvents and reaction conditions used in thepreparation of the complex itself. By the term "noninterfering oxidizingagent" is meant a compound having an oxidation potential sufficient toraise the metal oxidation state without interfering with the desiredcomplex formation or subsequent polymerization processes. A particularlysuitable noninterfering oxidizing agent is AgCl or an organic halidesuch as methylene chloride. The foregoing techniques are disclosed inU.S. Ser. Nos.: 545,403, filed Jul. 3, 1990 and 702,475, filed May 20,1991, the teachings of both of which are incorporated herein byreference.

Additionally the complexes may be prepared according to the teachings ofthe copending application entitled: "Preparation of Metal CoordinationComplex (I)", filed in the names of Peter Nickias and David Wilson, onOct. 15, 1991 and the copending application entitled: "Preparation ofMetal Coordination Complex (II)", filed in the names of Peter Nickiasand David Devore, on Oct. 15, 1991, the teachings of which areincorporated herein by reference thereto.

Suitable cocatalysts for use herein include polymeric or oligomericalumoxanes, especially methyl alumoxane, as well as inert, compatible,noncoordinating, ion forming compounds. Preferred cocatalysts are inert,noncoordinating, boron compounds.

Ionic active catalyst species which can be used to polymerize thepolymers described herein correspond to the formula: ##STR4## wherein:

M is a metal of group 3-10, or the Lanthanide series of the PeriodicTable of the Elements;

Cp* is a cyclopentadienyl or substituted cyclopentadienyl group bound inan η⁵ bonding mode to M;

Z is a moiety comprising boron, or a member of group 14 of the PeriodicTable of the Elements, and optionally sulfur or oxygen, said moietyhaving up to 20 non-hydrogen atoms, and optionally Cp* and Z togetherform a fused ring system;

X independently each occurrence is an anionic ligand group or neutralLewis base ligand group having up to 30 non-hydrogen atoms;

n is 0, 1 , 2, 3, or 4 and is 2 less than the valence of M; and

A⁻ is a noncoordinating, compatible anion.

One method of making the ionic catalyst species which can be utilized tomake the polymers of the present invention involve combining:

a) at least one first component which is a mono(cyclopentadienyl)derivative of a metal of Group 3-10 or the Lanthanide Series of thePeriodic Table of the Elements containing at least one substituent whichwill combine with the cation of a second component (describedhereinafter) which first component is capable of forming a cationformally having a coordination number that is one less than its valence,and

b) at least one second component which is a salt of a Bronsted acid anda noncoordinating, compatible anion.

More particularly the noncoordinating, compatible anion of the Bronstedacid salt may comprise a single coordination complex comprising acharge-bearing metal or metalloid core, which anion is both bulky andnon-nucleophilic. The recitation "metalloid", as used herein, includesnon-metals such as boron, phosphorus and the like which exhibitsemi-metallic characteristics.

Illustrative, but not limiting examples of monocyclopentadienyl metalcomponents (first components) which may be used in the preparation ofcationic complexes are derivatives of titanium, zirconium, hafnium,chromium, lanthanum, etc. Preferred components are titanium or zirconiumcompounds. Examples of suitable monocyclopentadienyl metal compounds arehydrocarbyl-substituted monocyclopentadienyl metal compounds such as(tert-butylamido)(tetramethyl-η⁵-cyclopentadienyl)-1,2-ethanediylzirconium dimethyl,(tert-butylamido)(tetramethyl-η⁵-cyclopentadienyl)-1,2-ethanediyltitanium dimethyl,(methylamido)(tetramethyl-η⁵ -cyclopentadienyl)-1,2-ethanediylzirconiumdibenzyl, (methylamido)(tetramethyl-η⁵-cyclopentadienyl)-1,2-ethanediyltitanium dimethyl,(ethylamido)(tetramethyl-η⁵ -cyclopentadienyl)-methylenetitaniumdimethyl, (tert-butylamido)dibenzyl(tetramethyl-η⁵-cyclopentadienyl)silanezirconium dibenzyl,(benzylamido)dimethyl(tetramethyl-η⁵ -cyclopentadienyl)silanetitaniumdiphenyl, (phenylphosphido)dimethyl(tetramethyl-η⁵-cyclopentadienyl)silanezirconium dibenzyl, and the like.

Such components are readily prepared by combining the correspondingmetal chloride with a dilithium salt of the substituted cyclopentadienylgroup such as a cyclopentadienyl-alkanediyl, cyclopentadienyl--silaneamide, or cyclopentadienyl--phosphide compound. The reaction isconducted in an inert liquid such as tetrahydrofuran, C₅₋₁₀ alkanes,toluene, etc. utilizing conventional synthetic procedures. Additionally,the first components may be prepared by reaction of a group IIderivative of the cyclopentadienyl compound in a solvent and separatingthe salt by-product. Magnesium derivatives of the cyclopentadienylcompounds are preferred. The reaction may be conducted in an inertsolvent such as cyclohexane, pentane, tetrahydrofuran, diethyl ether,benzene, toluene, or mixtures of the like. The resulting metalcyclopentadienyl halide complexes may be alkylated using a variety oftechniques. Generally, the metal cyclopentadienyl alkyl or arylcomplexes may be prepared by alkylation of the metal cyclopentadienylhalide complexes with alkyl or aryl derivatives of group I or group IImetals. Preferred alkylating agents are alkyl lithium and Grignardderivatives using conventional synthetic techniques. The reaction may beconducted in an inert solvent such as cyclohexane, pentane,tetrahydrofuran, diethyl ether, benzene, toluene, or mixtures of thelike. A preferred solvent is a mixture of toluene and tetrahydrofuran.

Compounds useful as a second component in the preparation of the ioniccatalysts useful in this invention will comprise a cation, which is aBronsted acid capable of donating a proton, and a compatiblenoncoordinating anion. Preferred anions are those containing a singlecoordination complex comprising a charge-bearing metal or metalloid corewhich anion is relatively large (bulky), capable of stabilizing theactive catalyst species (the Group 3-10 or Lanthanide Series cation)which is formed when the two components are combined and sufficientlylabile to be displaced by olefinic, diolefinic and acetylenicallyunsaturated substrates or other neutral Lewis bases such as ethers,nitriles and the like. Suitable metals, then, include, but are Rotlimited to, aluminum, gold, platinum and the like. Suitable metalloidsinclude, but are not limited to, boron, phosphorus, silicon and thelike. Compounds containing anions which comprise coordination complexescontaining a single metal or metalloid atom are, of course, well knownand many, particularly such compounds containing a single boron atom inthe anion portion, are available commercially. In light of this, saltscontaining anions comprising a coordination complex containing a singleboron atom are preferred.

Highly preferably, the second component useful in the preparation of thecatalysts of this invention may be represented by the following generalformula:

    (L-H).sup.+ [A]

wherein:

L is a neutral Lewis base;

(L-H)⁺ is a Bronsted acid; and

[A]⁻ is a compatible, noncoordinating anion.

More preferably [A]⁻ corresponds to the formula:

    [M'Q.sub.q ].sup.-

wherein:

M' is a metal or metalloid selected from Groups 5-15 of the PeriodicTable of the Elements; and

Q independently each occurrence is selected from the Group consisting ofhydride, dialkylamido, halide, alkoxide, aryloxide, hydrocarbyl, andsubstituted-hydrocarbyl radicals of up to 20 carbons with the provisothat in not more than one occurrence is Q halide and

q is one more than the valence of M'.

Second components comprising boron which are particularly useful in thepreparation of catalysts of this invention may be represented by thefollowing general formula:

    [L-H].sup.+ [BQ.sub.4 ]

wherein:

L is a neutral Lewis base;

[L-H]⁺ is a Bronsted acid;

B is boron in a valence state of 3; and

Q is as previously defined.

Illustrative, but not limiting, examples of boron compounds which may beused as a second component in the preparation of the improved catalystsof this invention are trialkyl-substituted ammonium salts such astriethylammonium tetraphenylborate, tripropylammonium tetraphenylborate,tri(n-butyl)ammonium tetraphenylborate, trimethylammoniumtetra(p-tolylborate), tributylammonium tetrakis-pentafluorophenylborate,tripropylammonium tetrakis-2,4-dimethylphenylborate, tributylammoniumtetrakis-3,5-dimethylphenylborate, triethylammoniumtetrakis-(3,5-di-trifluoromethylphenyl)borate and the like. Alsosuitable are N,N-dialkyl anilinium salts such as N,N-dimethylaniliniumtetraphenylborate, N,N-diethylanilinium tetraphenylborate,N,N-2,4,6-pentamethylanilinium tetraphenylborate and the like; dialkylammonium salts such as di-(i-propyl)ammoniumtetrakispentafluorophenylborate, dicyclohexylammonium tetraphenylborateand the like; and triaryl phosphonium salts such as triphenylphosphoniumtetraphenylborate, tri(methylphenyl)phosphoniumtetrakis-pentafluorophenylborate, tri(dimethylphenyl)phosphoniumtetraphenylborate and the like.

Preferred ionic catalysts are those having a limiting charge separatedstructure corresponding to the formula: ##STR5## wherein:

M is a metal of group 3-10, or the Lanthanide series of the PeriodicTable of the Elements;

Cp* is a cyclopentadienyl or substituted cyclopentadienyl group bound inan η⁵ bonding mode to M;

Z is a moiety comprising boron, or a member of group 14 of the PeriodicTable of the Elements, and optionally sulfur or oxygen, said moietyhaving up to 20 non-hydrogen atoms, and optionally Cp* and Z togetherform a fused ring system;

X independently each occurrence is an anionic ligand group or neutralLewis base ligand group having up to 30 non-hydrogen atoms;

n is 0, 1, 2, 3, or 4 and is 2 less than the valence of M; and

    XA*- is .sup.- XB(C.sub.6 F.sub.5).sub.3.

This class of cationic complexes may be conveniently prepared bycontacting a metal compound corresponding to the formula: ##STR6##wherein:

Cp, M, and n are as previously defined,

with tris(pentafluorophenyl)borane cocatalyst under conditions to causeabstraction of X and formation of the anion ⁻ XB(C₆ F₅)₃.

Preferably X in the foregoing ionic catalyst is C₁ -C₁₀ hydrocarbyl,most preferably methyl.

The preceding formula is referred to as the limiting, charge separatedstructure. However, it is to be understood that, particularly in solidform, the catalyst may not be fully charge separated. That is, the Xgroup may retain a partial covalent bond to the metal atom, M. Thus, thecatalysts may be alternately depicted as possessing the formula:##STR7##

The catalysts are preferably prepared by contacting the derivative of aGroup 4 or Lanthanide metal with the tris(pentafluorophenyl)borane in aninert diluent such as an organic liquid.

Tris(pentafluorphenyl)borane is a commonly available Lewis acid that maybe readly prepared according to known techniques. The compound isdisclosed in Marks, et al. J. Am. Chem. Soc. 1991, 113, 3623-3625 foruse in alkyl abstraction of zirconocenes.

All reference to the Periodic Table of the Elements herein shall referto the Periodic Table of the Elements, published and copyrighted by CRCPress, Inc., 1989. Also, any reference to a Group or Groups shall be tothe Group or Groups as reflected in this Periodic Table of the Elementsusing the IUPAC system for numbering groups.

It is believed that in the constrained geometry catalysts used hereinthe metal atom is forced to greater exposure of the active metal sitebecause one or more substituents on the single cyclopentadienyl orsubstituted cyclopentadienyl group forms a portion of a ring structureincluding the metal atom, wherein the metal is both bonded to anadjacent covalent moiety and held in association with thecyclopentadienyl group through an η⁵ or other η-bonding interaction. Itis understood that each respective bond between the metal atom and theconstituent atoms of the cyclopentadienyl or substitutedcyclopentadienyl group need not be equivalent. That is, the metal may besymmetrically or unsymmetrically π-bound to the cyclopentadienyl orsubstituted cyclopentadienyl group.

The geometry of the active metal site is further defined as follows. Thecentroid of the cyclopentadienyl or substituted cyclopentadienyl groupmay be defined as the average of the respective X, Y, and Z coordinatesof the atomic centers forming the cyclopentadienyl or substitutedcyclopentadienyl group. The angle, Θ, formed at the metal center betweenthe centroid of the cyclopentadienyl or substituted cyclopentadienylgroup and each other ligand of the metal complex may be easilycalculated by standard techniques of single crystal X-ray diffraction.Each of these angles may increase or decrease depending on the molecularstructure of the constrained geometry metal complex. Those complexeswherein one or more of the angles, Θ, is less than in a similar,comparative complex differing only in the fact that theconstrain-inducing substituent is replaced by hydrogen have constrainedgeometry for purposes of the present invention. Preferably one or moreof the above angles, Θ, decrease by at least 5 percent, more preferably7.5 percent, compared to the comparative complex. Highly preferably, theaverage value of all bond angles, Θ, is also less than in thecomparative complex.

Preferably, monocyclopentadienyl metal coordination complexes of group 4or lanthanide metals according to the present invention have constrainedgeometry such that the smallest angle, Θ, is less than 115°, morepreferably less than 110°, most preferably less than 105°.

Other compounds which are useful in the catalyst compositions of thisinvention, especially compounds containing other Group 4 or Lanthanidemetals, will, of course, be apparent to those skilled in the art.

In general, the polymerization according to the present invention may beaccomplished at conditions well known in the prior art for Ziegler-Nattaor Kaminsky-Sinn type polymerization reactions, that is, temperaturesfrom 0° to 250° C. and pressures from atmospheric to 1000 atmospheres(100 MPa). Suspension, solution, slurry, gas phase or other processconditions may be employed if desired. A support may be employed butpreferably the catalysts are used in a homogeneous manner. It will, ofcourse, be appreciated that the active catalyst system, especiallynonionic catalysts, form in situ if the catalyst and the cocatalystcomponents thereof are added directly to the polymerization process anda suitable solvent or diluent, including condensed monomer, is used insaid polymerization process. It is, however, preferred to form theactive catalyst in a separate step in a suitable solvent prior to addingthe same to the polymerization mixture.

The polymerization conditions for manufacturing the polymers of thepresent invention are generally those useful in the solutionpolymerization process, although the application of the presentinvention is not limited thereto. Gas phase polymerization processes arealso believed to be useful, provided the proper catalysts andpolymerization conditions are employed.

Fabricated articles made from the novel olefin polymers may be preparedusing all of the conventional polyolefin processing techniques. Usefularticles include films (e.g., cast, blown and extrusion coated), fibers(e.g., staple fibers (include-nu use of a novel olefin polymer disclosedherein as at least one component comprising at least a portion of thefiber's surface), spunbond fibers or melt blown fibers (using, e.g.,systems as disclosed in U.S. Pat. No. 4,430,563, U.S. Pat. No.4,663,220, U.S. Pat. No. 4,668,566, or U.S. Pat. No. 4,322,027, all ofwhich are incorporated herein by reference), and gel spun fibers (e.g.,the system disclosed in U.S. Pat. No. 4,413,110, incorporated herein byreference)), both woven and nonwoven fabrics (e.g., spunlaced fabricsdisclosed in U.S. Pat. No. 3,485,706, incorporated herein by reference)or structures made from such fibers (including, e.g., blends of thesefibers with other fibers, e.g., PET or cotton) and molded articles(e.g., made using an injection molding process, a blow molding processor a rotomolding process). The new polymers described herein are alsouseful for wire and cable coating operations, as well as in sheetextrusion for vacuum forming operations.

Useful compositions are also suitably prepared comprising thesubstantially linear polymers of the present invention and at least oneother natural or synthetic polymer. Preferred other polymers includethermoplastics such as styrene-butadiene block copolymers, polystyrene(including high impact polystyrene), ethylene vinyl alcohol copolymers,ethylene acrylic acid copolymers, other olefin copolymers (especiallypolyethylene copolymers) and homopolymers (e.g., those made usingconventional heterogeneous catalysts). Examples include polymers made bythe process of U.S. Pat. No. 4,076,698, incorporated herein byreference, other linear or substantially linear polymers of the presentinvention, and mixtures thereof. Other substantially linear polymers ofthe present invention and conventional HDPE and/or LLDPE are preferredfor use in the thermoplastic compositions.

Compositions comprising the olefin polymers can also be formed intofabricated articles such as those previously mentioned usingconventional polyolefin processing techniques which are well known tothose skilled in the art of polyolefin processing.

All procedures were performed under an inert atmosphere or nitrogen orargon. Solvent choices were often optional, for example, in most caseseither pentane or 30-60 petroleum ether can be interchanged. Amines,silanes, lithium reagents, and Grignard reagents were purchased fromAldrich Chemical Company. Published methods for preparingtetramethylcyclopentadiene (C₅ Me₄ H₂) and lithiumtetramethylcyclopentadienide (Li(C₅ Me₄ H)) include C. M. Fendrick etal. Organometallics, 3, 819 (1984). Lithiated substitutedcyclopentadienyl compounds may be typically prepared from thecorresponding cyclopentadiene and a lithium reagent such as n-butyllithium. Titanium trichloride (TiCl₃) was purchased from AldrichChemical Company. The tetrahydrofuran adduct of titanium trichloride,TiCl₃ (THF)₃, was prepared by refluxing TiCl₃ in THF overnight, cooling,and isolating the blue solid product, according to the procedure of L.E. Manzer, Inorg. Syn., 21, 135 (1982).

EXAMPLES 1-4

The metal complex solution for Example 1 is prepared as follows:

Part 1: Prep of Li(C₅ Me₄ H)

In the drybox, a 3 L 3-necked flask was charged with 18.34 g of C₅ Me₄H₂, 800 mL of pentane, and 500 mL of ether. The flask was topped with areflux condenser, a mechanical stirrer, and a constant addition funnelcontainer 63 mL of 2.5M n-BuLi 4Ln hexane. The BuLi was added dropwiseover several hours. A very thick precipitate formed: approx. 1000 mL ofadditional pentane had to be added over the course of the reaction toallow stirring to continue. After the addition was complete, the mixturewas stirred overnight. The next day, the material was filtered, and thesolid was thoroughly washed with pentane and then dried under reducedpressure. 14.89 g of Li(C₅ Me₄ H) was obtained (78 percent).

Part 2: Prep of C₅ Me₄ HSiMe₂ Cl

In the drybox 30.0 g of Li(C₅ Me₄ H) was placed in a 500 mL Schlenkflask with 250 mL of THF and a large magnetic stir bar. A syringe wascharged with 30 mL of Me₂ SiCl₂ and the flask and syringe were removedfrom the drybox. On the Schlenk line under a flow of argon, the flaskwas cooled to -78° C., and the Me₂ SiCl₂ added in one rapid addition.The reaction was allowed to slowly warm to room temperature and stirredovernight. The next morning the volatile materials were removed underreduced pressure, and the flask was taken into the drybox. The oilymaterial was extracted with pentane, filtered, and the pentane wasremoved under reduced pressure to leave the C₅ Me₄ HSiMe₂ Cl as a clearyellow liquid (46.83 g; 92.9 percent).

Part 3: Prep of C₅ Me₄ HSiMe₂ NH^(t) Bu

In the drybox, a 3-necked 2 L flask was charged with 37.4 g oft-butylamine and 210 mL of THF. C₅ Me₄ HSiMe₂ Cl (25.47 g) was slowlydripped into the solution over 3-4 hours. The solution turned cloudy andyellow. The mixture was stirred overnight and the volatile materialsremoved under reduced pressure. The residue was extracted with diethylether, the solution was filtered, and the ether removed under reducedpressure to leave the C₅ Me₄ HSiMe₂ NH^(t) Bu as a clear yellow liquid(26.96 g; 90.8 percent).

Part 4: Prep [MgCl]₂ [Me₄ C₅ SiMe₂ N^(t) Bu](THF)_(x)

In the drybox, 14.0 mL of 2.0M isopropylmagnesium chloride in ether wassyringed into a 250 mL flask. The ether was removed under reducedpressure to leave a colorless oil. 50 mL of a 4:1 (by volume)toluene:THF mixture was added followed by 3.50 g of Me₄ HC₅ SiMe₂ NH^(t)BU. The solution was heated to reflux. After refluxing for 2 days, thesolution was cooled and the volatile materials removed under reducedpressure. The white solid residue was slurried in pentane and filteredto leave a white powder, which was washed with pentane and dried underreduced pressure. The white powder was identified as [MgCl]₂ [Me₄ C₅SiMe₂ N^(t) Bu](THF)_(x) (yield: 6.7 g).

Part 5: Prep of [C₅ Me₄ (SiMe₂ N^(t) Bu)]TiCl₂

In the drybox, 0.50 g of TiCl₃ (THF)₃ was suspended in 10 mL of THF.0.69 g of solid [MgCl]₂ [Me₄ C₅ SiMe₂ N^(t) Bu](THF)_(x) was added,resulting in a color change from pale blue to deep purple. After 15minutes, 0.35 g of AgCl was added to the solution. The color immediatelybegan to lighten to a pale green-yellow. After 11/2 hours, the THF wasremoved under reduced pressure to leave a yellow-green solid. Toluene(20 mL) was added, the solution was filtered, and the toluene wasremoved under reduced pressure to leave a yellow-green solid, 0.51 g(quantitative yield) identified by 1H NMR as [C₅ Me₄ (SiMe₂ N^(t)Bu)]TiCl₂.

Part 6: Preparation of [C₅ Me₄ (SiMe₂ N^(t) Bu)]TiMe₂

In an inert atmosphere glove box, 9.031 g of [C₅ Me₄ (Me₂ SiN^(t)Bu)]TiCl₂ is charged into a 250 ml flask and dissolved into 100 ml ofTHF. This solution is cooled to about -25° C. by placement in the glovebox freezer for 15 minutes. To the cooled solution is added 35 ml of a1.4M MeMgBr solution in toluene/THF (75/25). The reaction mixture isstirred for 20 to 25 minutes followed by removal of the solvent undervacuum. The resulting solid is dried under vacuum for several hours. Theproduct is extracted with pentane (4×50 ml) and filtered. The filtrateis combined and the pentane removed under vacuum giving the catalyst asa straw yellow solid.

The metal complex, [C₅ Me₄ (SiMe₂ N^(t) Bu)]TiMe₂, solution for Examples2 and 3 is prepared as follows:

In an inert atmosphere glove box 10.6769 g of a tetrahydrofuran adductof titanium trichloride, TiCl₃ (THF )₃, is loaded into a 1 l flask andslurried into ≈300 ml of THF. To this slurry, at room temperature, isadded 17.402 g of [MgCl]₂ [N^(t) BuSiMe₂ C₅ Me₄ ] (THF)_(x) as a solid.An additional 200 ml of THF is used to help wash this solid into thereaction flask. This addition resulted in an immediate reaction giving adeep purple solution. After stirring for 5 minutes 9.23 ml of a 1.56Msolution of CH₂ Cl₂ in THF is added giving a quick color change to darkyellow. This stage of the reaction is allowed to stir for about 20 to 30minutes. Next, 61.8 m l of a 1.4M MeMgBr solution in toluene/THF(75/25)is added via syringe. After about 20 to 30 minutes stirring tame thesolvent is removed under vacuum and the solid dried. The product isextracted with pentane (8×50 ml) and filtered. The filtrate is combinedand the pentane removed under vacuum giving the metal complex as a tansolid.

The metal complex, [C₅ Me₄ (SiMe₂ N^(t) Bu)]TiMe₂, solution for Example4 is prepared as follows:

In an inert atmosphere glove box 4.8108 g of TiCl₃ (thf)₃ is placed in a500 ml flask and slurried into 130 ml of THF. In a separate flask 8.000g of [MgCl]₂ [N^(t) BuSiMe₂ C₅ Me₄ ](THF)_(x) is dissolved into 150 mlof THF. These flasks are removed from the glove box and attached to avacuum line and the contents cooled to -30° C. The THF solution of[MgCl]₂ [N^(t) BuSiMe₂ C₅ Me₄ ](THF)_(x) is transferred (over a 15minute period) via cannula to the flask containing the TiCl₃ (THF)₃slurry. This reaction is allowed to stir for 1.5 hours over which timethe temperature warmed to 0° C. and the solution color turned deeppurple. The reaction mixture is cooled back to -30° C. and 4.16 ml of a1.56M CH₂ Cl₂ solution in THF is added. This stage of the reaction isstirred for an additional 1.5 hours and the temperature warmed to -10°C. Next, the reaction mixture is again cooled to -40° C. and 27.81 ml ofa 1.4M MeMgBr solution in toluene/THF (75/25) was added via syringe andthe reaction is now allowed to warm slowly to room temperature over 3hours. After this time the solvent is removed under vacuum and the soliddried. At this point the reaction flask is brought back into the glovebox where the product is extracted with pentane (4×50 ml) and filtered.The filtrate is combined and the pentane removed under vacuum giving thecatalyst as a tan solid. The metal complex is then dissolved into amixture of C₈ -C₁₀ saturated hydrocarbons (e.g. , Isopar® E, made byExxon) and ready for use in polymerization.

Polymerization

The polymer products of Examples 1-4 are produced in a solutionpolymerization process using a continuously stirred reactor. Additives(e.g., antioxidants, pigments, etc.) can be incorporated into theinterpolymer products either during the pelletization step or aftermanufacture, with a subsequent re-extrusion. Examples 1-4 are eachstabilized with 1250 ppm Calcium Stearate, 200 ppm IRGANOX 1010, and1600 ppm Irgafos 168, Irgafos™ 168 is a phosphite stabilizer andIRGANOX™ 1010 is a hindered polyphenol stabilizer (e.g., tetrakis[methylene 3-(3,5-ditert.butyl-4-hydroxy-phenylpropionate)]methane. Bothare trademarks of and made by Ciba-Geigy Corporation. A representativeschematic for the polymerization process is shown in FIG. 1.

The ethylene (4) and the hydrogen are combined into one, stream (15)before being introduced into the diluent mixture (3). Typically, thediluent mixture comprises a mixture of C₈ -C₁₀ saturated hydrocarbons(1), (e.g., Isopar® E, made by Exxon) and the comonomer(s) (2). Forexamples 1-4, the comonomer is 1-octene. The reactor feed mixture (6) iscontinuously injected into the reactor (9). The metal complex (7) andthe cocatalyst (8) (the cocatalyst is tris(pentafluorophenyl)borane forExamples 1-4 herein which forms the ionic catalyst insitu) are combinedinto a single stream and also continuously injected into the reactor.Sufficient residence time is allowed for the metal complex andcocatalyst to react to the desired extent for use in the polymerizationreactions, at least about 10 seconds. For the polymerization reactionsof Examples 1-4. the reactor pressure is held constant at about 490psig. Ethylene content of the reactor, after reaching steady state, ismaintained below about 8 percent.

After polymerization, the reactor exit stream (14) is introduced into aseparator (10) where the molten polymer is separated from the unreactedcomonomer(s), unreacted ethylene, unreacted hydrogen, and diluentmixture stream (13). The molten polymer is subsequently strand choppedor pelletized and, after being cooled in a water bath or pelletizer(11), the solid pellets are collected (12). Table I describes thepolymerization conditions and the resultant polymer properties:

                  TABLE I                                                         ______________________________________                                        Example     1         2         3     4                                       ______________________________________                                        Ethylene feed                                                                             3.2       3.8       3.8   3.8                                     rate                                                                          (lbs/hour)                                                                    Comonomer/  12.3      0         0     0                                       Olefin* ratio                                                                 (mole %)                                                                      Hydrogen/   0.054     0.072     0.083 0.019                                   Ethylene ratio                                                                (mole %)                                                                      Diluent/    9.5       7.4       8.7   8.7                                     Ethylene ratio                                                                (weight basis)                                                                metal complex                                                                             0.00025   0.0005    0.001 0.001                                   concentration                                                                 (molar)                                                                       metal complex                                                                             5.9       1.7       2.4   4.8                                     flow rate                                                                     (ml/min)                                                                      cocatalyst  0.001     0.001     0.002 0.002                                   concentration                                                                 (molar)                                                                       cocatalyst  2.9       1.3       6     11.9                                    flow rate                                                                     (ml/min)                                                                      Reactor     114       160       160   200                                     temperature                                                                   (°C.)                                                                  Ethylene Conc.                                                                            2.65      3.59      0.86  1.98                                    in the reactor                                                                exit steam                                                                    (weight percent)                                                              Product I.sub.2                                                                           1.22      0.96      1.18  0.25                                    (g/10 minutes)                                                                Product density                                                                           0.903     0.954     0.954 0.953                                   (g/cc)                                                                        Product I.sub.10 /I.sub.2                                                                 6.5       7.4       11.8  16.1                                    Product     1.86      1.95      2.09  2.07                                    M.sub.w /M.sub.n                                                              ______________________________________                                         *For Examples 1-4, the Comonomer/Olefin ratio is defined as the percentag     molar ratio of ((1octene/(1-octene + ethylene))                          

The ¹³ C NMR spectrum of Example 3 (ethylene homopolymer) shows peakswhich can be assigned to the αδ+, βδ+, and methine carbons associatedwith a long chain branch. Long chain branching is determined using themethod of Randall described earlier in this disclosure, wherein hestates that "Detection of these resonances in high-density polyethyleneswhere no 1-olefins were added during the polymerization should bestrongly indicative of the presence of long chain branching." Using theequation 141 from Randall (p. 292):

    Branches per 10,000 carbons=[1/3α/T.sub.Tot)]×10.sup.4,

wherein α=the average intensity of a carbon from a branch (αδ+) carbonand T_(Tot) =the total carbon intensity,

the number of long chain branches in this sample is determined to be 3.4per 10,000 carbon atoms, or 0.34 long chain branches/1000 carbon atoms.

EXAMPLES 5, 6 and COMPARATIVE EXAMPLES 7-9

Examples 5, 6 and comparison examples 7-9 with the same melt index aretested for rheology comparison. Examples 5 and 6 are the substantiallylinear polyethylenes produced by the constrained geometry catalysttechnology, as described in Examples 1-4. Examples 5 and 6 are stablizedas Examples 1-4.

Comparison examples 7, 8 and 9 are conventional heterogeneous Zieglerpolymerization blown film resins Dowlex® 2045A, Attane® 4201, andAttane® 4403, respectively, all of which are ethylene/1-octenecopolymers made by The Dow Chemical Company. Comparative example 7 isstablized with 200 ppm IRGANOX® 1010, and 1600 ppm Irgafos® 168 whilecomparative examples 8 and 9 are stablized with 200 ppm IRGANOX® 1010and 800 ppm PEPQ®. PEPQ® is a trademark of Sandoz Chemical, the primaryingredient of which is believed to betetrakis-(2,4-di-tertbutyl-phenyl)-4,4' biphenylphosphonite.

A comparison of the physical properties of each example and comparativeexample is listed in Table II.

                                      TABLE II                                    __________________________________________________________________________          Example                                                                             Example                                                                             Comparison                                                                           Comparison                                                                           Comparison                                    Property                                                                            5     6     Example 7                                                                            Example 8                                                                            Example 9                                     __________________________________________________________________________    I.sub.2                                                                             1     1     1      1      0.76                                          density                                                                             .92   .902  .92    .912   .905                                          I.sub.10 /I.sub.2                                                                   9.45  7.61  7.8-8  8.2    8.7                                           M.sub.w /M.sub.n                                                                    1.97  2.09  3.5-3.8                                                                              3.8    3.8-4.0                                       __________________________________________________________________________

Surprisingly, even though the molecular weight distribution of Examples5 and 6 is narrow (i.e., M_(w) /M_(n) is low) , the I₁₀ /I₂ values arehigher in comparison with comparative examples 7-9. A comparison of therelationship between I₁₀ /I₂ vs. M_(w) /M_(n) for some of the novelpolymers described herein and conventional heterogeneous Zieglerpolymers is given in FIG. 2. The I₁₀ /I₂ value for the novel polymers ofthe present invention is essentially independent of the molecular weightdistribution, M_(w) /M_(n), which is not true for conventional Zieglerpolymerized resins.

Example 5 and comparison example 7 with similar melt index and density(Table II) are also extruded via a Gas Extrusion Rheometer (GER) at 190°C. using a 0.0296" diameter, 20 L/D die. The processing index (P.I.) ismeasured at an apparent shear stress of 2.15×10⁶ dyne/cm² as describedpreviously. The onset of gross melt fracture can easily be identifiedfrom the shear stress vs. shear rate plot shown in FIG. 3 where a suddenjump of shear rate occurs. A comparison of the shear stresses andcorresponding shear rates before the onset of gross melt fracture islisted in Table III. It is particularly interesting that the PI ofExample 5 is more than 20% lower than the PI of comparative example 7and that the onset of melt fracture or sharkskin for Example 5 is alsoat a significantly higher shear stress and shear rate in comparison withthe comparative example 7. Furthermore, the Melt Tension (MT) as well asElastic Modulus of Example 5 are higher than that of comparative example7.

                  TABLE III                                                       ______________________________________                                                                   Comparison                                         Property       Example 5   example 7                                          ______________________________________                                        I.sub.2        1           1                                                  I.sub.10 /I.sub.2                                                                            9.45        7.8-8                                              PI, kpoise     11          15                                                 Melt Tension   1.89        1.21                                               Elastic Modulus                                                                              2425        882.6                                              @.1 rad/sec.                                                                  (dyne/cm.sup.2)                                                               OGMF*, critical                                                                              >1556       936                                                shear rate (1/sec)                                                                           (not observed)                                                 OGMF*, critical                                                                              .452        .366                                               shear stress (MPa)                                                            OSMF**, critical                                                                             >1566       ˜628                                         shear rate (1/sec.)                                                                          (not observed)                                                 OSMF**, critical                                                                             ˜0.452                                                                              ˜0.25                                        shear stress (MPa)                                                            ______________________________________                                         *Onset of Gross Melt Fracture.                                                **Onset of Surface Melt Fracture.                                        

Example 6 and comparison example 9 have similar melt index and density,but example 6 has lower I₁₀ /I₂ (Table IV). These polymers are extrudedvia a Gas Extrusion Rheometer (GER) at 190° C. using a 0.0296 inchdiameter, 20:1 L/D die. The processing index (PI) is measured at anapparent shear stress of 2.15×10⁶ dyne/cm² as described previously.

                  TABLE IV                                                        ______________________________________                                                                   Comparison                                         Property       Example 6   example 9                                          ______________________________________                                        I.sub.2 (g/10 minutes)                                                                       1           0.76                                               I.sub.10 /I.sub.2                                                                            7.61        8.7                                                PI (kpoise)    14          15                                                 Melt Tension (g)                                                                             1.46        1.39                                               Elastic Modulus                                                                              1481        1921                                               @ 0.1 rad/sec                                                                 (dyne/cm2)                                                                    OGMF*, critical                                                                              1186        652                                                shear rate (1/sec)                                                            OGMF*, critical                                                                              0.431       0.323                                              shear stress (MPa)                                                            OSMF**, critical                                                                             ˜764  ˜402                                         shear rate (1/sec.)                                                           OSMF**, critical                                                                             0.366       0.280                                              shear stress (MPa)                                                            ______________________________________                                         *Onset of Gross Melt Fracture.                                                **Onset of Surface Melt Fracture.                                        

The onset of gross melt fracture can easily be identified from the shearstress vs. shear rate plot shown in FIG. 4 where a sudden increase ofshear rate occurs at an apparent shear stress of about 3.23×10⁶ dyne/cm²(0.323 Mpa). A comparison of the shear stresses and corresponding shearrates before the onset of gross melt fracture is listed in Table IV. ThePI of Example 6 is surprisingly about the same as comparative example 9,even though the I₁₀ /I₂ is lower for Example 6. The onset of meltfracture or sharkskin for Example 6 is also at a significantly highershear stress and shear rate in comparison with the comparative example9. Furthermore, it is also unexpected that the Melt Tension (MT) ofExample 6 is higher than that of comparative example 9, even though themelt index for Example 6 is slightly higher and the I₁₀ /I₂ is slightlylower than that of comparative example 9.

EXAMPLE 10 AND COMPARATIVE EXAMPLE 11

Blown film is fabricated from two novel ethylene/1-octene polymers madein accordance with the present invention and from two comparativeconventional polymers made according to conventional Ziegler catalysis.The blown films are tested for physical properties, including heat sealstrength versus heat seal temperature (shown in FIG. 5 for Examples 10and 12 and comparative examples 11 and 13). machine (MD) and crossdirection (CD) properties (e.g., tensile yield and break, elongation atbreak and Young's modulus). Other film properties such as dart,puncture, tear, clarity, haze, 20 degree gloss and block are alsotested.

Blown Film Fabrication Conditions

The improved processing substantially linear polymers of the presentinvention produced via the procedure described earlier, as well as twocomparative resins are fabricated on an Egan blown film line using thefollowing fabrication conditions:

2 inch extruder

3 inch die

30 mil die gap

25 RPM extruder speed

460° F. melt temperature

1 mil gauge

2.7:1 Blow up ratio (12.5 inches layflat)

12.5 inches frost line height

The melt temperature is kept constant by changing the extrudertemperature profile. Frost line height is maintained at 12.5 inches byadjusting the air flow. The extruder output rate, back pressure andpower consumption in amps are monitored throughout the experiment. Thepolymers of the present invention and the comparative polymers are allethylene/1-octene copolymers. Table VI summarizes physical properties ofthe two polymers of the invention and for the two comparative polymers:

                  TABLE VI                                                        ______________________________________                                                Example  Comparative                                                                              Example                                                                              Comparative                                Property                                                                              10       example 11 12     example 13                                 ______________________________________                                        I.sub.2 1        1          1      0.8                                        (g/10                                                                         minutes)                                                                      Density 0.92     0.92       0.902  0.905                                      (g/cc)                                                                        I.sub.10 /I.sub.2                                                                     9.45     ˜8   7.61   8.7                                        M.sub.w /M.sub.n                                                                      2        ˜5   2      ˜5                                   ______________________________________                                    

Tables VII and VIII summarize the film properties measured for blownfilm made from two of these four polymers:

                  TABLE VII                                                       ______________________________________                                        Blown film properties                                                                   Example         Comparative                                                   10              example 11                                          Property    MD      CD        MD    CD                                        ______________________________________                                        Tensile yield                                                                             1391    1340      1509  1593                                      (psi)                                                                         Tensile break                                                                             7194    5861      6698  6854                                      (psi)                                                                         elongation  650     668       631   723                                       (percent)                                                                     Young's     18990   19997     23086 23524                                     Modulus                                                                       (psi)                                                                         PPT* Tear   5.9     6.8       6.4   6.5                                       (gm)                                                                          ______________________________________                                         *Puncture Propagation Tear                                               

                  TABLE VIII                                                      ______________________________________                                                        Example  Comparative                                          Property        10       example 11                                           ______________________________________                                        Dart A (gm)     472      454                                                  Puncture (grams)                                                                              235      275                                                  clarity (percent)                                                                             71       68                                                   Haze            3.1      6.4                                                  20° gloss                                                                              114      81                                                   Block (grams)   148      134                                                  ______________________________________                                    

During the blown film fabrication, it is noticed that at the same screwspeed (25 rpm) and at the same temperature profile, the extruder backpressure is about 3500 psi at about 58 amps power consumption forcomparative example 11 and about 2550 psi at about 48 amps powerconsumption for example 10, thus showing the novel polymer of example 10to have improved processability over that of a conventionalheterogeneous Ziegler polymerized polymer. The throughput is also higherfor Example 10 than for comparative example 11 at the same screw speed.Thus, example 10 has higher pumping efficiency than comparative example11 (i.e., more polymer goes through per turn of the screw).

As FIG. 5 shows, the heat seal properties of polymers of the presentinvention are improved, as evidenced by lower heat seal initiationtemperatures and higher heat seal strengths at a given temperature, ascompared with conventional heterogeneous polymers at about the same meltindex and density.

What is claimed is:
 1. A substantially linear olefin polymercharacterized as having:a) a melt flow ratio, I₁₀ /I₂, ≧5.63, b) amolecular weight distribution, M_(w) /M_(n), defined by the equation:

    M.sub.w /M.sub.n ≦(I.sub.10 /I.sub.2)-4.63, and

c) a critical shear stress at onset of gross melt fracture of greaterthan about 4×10⁶ dyne/cm²,wherein the olefin polymer is furthercharacterized as a copolymer of ethylene with a C₃ -C₂₀ alpha-olefin. 2.The polymer of claim 1 wherein the M_(w) /M_(n) is less than about 3.5.3. The polymer of claim 1 wherein the M_(w) /M_(n) is from about 1.5 toabout 2.5.
 4. The polymer of claim 1 wherein the polymer has about 0.01to about 3 long chain branches/1000 carbons along the polymer backbone.5. The polymer of claim 4 having at least about 0.1 long chainbranches/1000 carbons along the polymer backbone.
 6. The polymer ofclaim 4 having at least about 0.3 long chain branches/1000 carbons alongthe polymer backbone.
 7. A composition comprising a substantially linearolefin polymer, wherein the polymer is characterized as having:a) a meltflow ratio, I₁₀ /I₂, ≧5.63, b) a molecular weight distribution, M_(w)/M_(n), defined by the equation:

    M.sub.w /M.sub.n ≦(I.sub.10 /I.sub.2)-4.63, and

c) a critical shear stress at onset of gross melt fracture of greaterthan about 4×10⁶ dyne/cm²,and at least one other natural or syntheticpolymer, wherein the substantially linear olefin polymer is furthercharacterized as a copolymer of ethylene with a C₃ -C₂₀ alpha-olefin. 8.The composition of claim 7 wherein the substantially linear olefinpolymer has a I₁₀ /I₂ up to about
 20. 9. The composition of claim 7wherein the substantially linear olefin polymer has a M_(w) /M_(n) lessthan about 3.5.
 10. The composition of claim 7 wherein the substantiallylinear olefin polymer has a M_(w) /M_(n) from about 1.5 to about 2.5.11. The composition of claim 7 wherein the synthetic polymer is aconventional ethylene homopolymer or copolymer.
 12. A substantiallylinear olefin polymer having a melt flow ratio, I₁₀ /I₂, ≦5.63, and amolecular weight distribution, M_(w) /M_(n), defined by the equation:

    M.sub.w /M.sub.n ≦(I.sub.10 /I.sub.2)-4.63,

produced by continuously contacting ethylene and a C₃ -C₂₀ alpha-olefinwith a catalyst composition under polymerization conditions, whereinsaid catalyst composition is characterized as: a) a metal coordinationcomplex comprising a metal atom of groups 3-10 or the Lanthanide seriesof the Periodic Table of the Elements and a delocalized π-bonded moietysubstituted with a constrain inducing moiety, said complex having aconstrained geometry about the metal atom such that the angle at themetal atom between the centroid of the delocalized, substituted π-bondedmoiety and the center of at least one remaining substituent is less thansuch angle in a similar complex containing a similar π-bonded moietylacking in such constrain-inducing substituent, and provided furtherthat for such complexes comprising more than one delocalized,substituted π-bonded moiety, only one thereof for each metal atom of thecomplex is a cyclic, delocalized, substituted π-bonded moiety, and b) anactivating cocatalyst.
 13. A substantially linear olefin polymercharacterized as having:a) a melt flow ratio, I₁₀ /I₂, ≧7, b) amolecular weight distribution, M_(w) /M_(n), of from about 1.5 to about2.5,wherein the substantially linear olefin polymer is furthercharacterized as a copolymer of ethylene with a C₃ -C₂₀ alpha-olefin.14. The polymer of claim 13 wherein the I₁₀ /I₂ is at least about
 8. 15.The polymer of claim 13 wherein the I₁₀ /I₂ is at least about
 9. 16. Thepolymer of claim 13 wherein the substantially linear olefin polymer isan ethylene/alpha-olefin copolymer.
 17. A substantially linear olefinpolymer having:(a) from about 0.01 to about 3 long chain branches/1000carbons along the polymer backbone and (b) a critical shear stress atonset of gross melt fracture of greater than about 4×10⁶dyne/cm²,wherein the substantially linear olefin polymer is furthercharacterized as a copolymer of ethylene with a C₃ -C₂₀ alpha-olefin.18. The polymer of claim 17 having at least about 0.1 long chainbranches/1000 carbons along the polymer backbone.
 19. The polymer ofclaim 17 having at least about 0.3 long chain branches/1000 carbonsalong the polymer backbone.
 20. The polymer of claim 17 wherein thepolymer has a I₁₀ /I₂ of at least about
 16. 21. The substantially linearolefin polymer of claim 1, wherein the polymer is a copolymer ofethylene and 1-octene.
 22. The substantially linear olefin polymer ofclaim 1, wherein the polymer is a copolymer of ethylene and 1-hexene.23. The substantially linear olefin polymer of claim 1, wherein thepolymer is a copolymer of ethylene and 1-butene.
 24. The substantiallylinear olefin polymer of claim 1, wherein the polymer is a copolymer ofethylene and 4-methyl-1-pentene.
 25. The composition of claim 7, whereinthe substantially linear olefin polymer is a copolymer of ethylene and1-octene.
 26. The composition of claim 7, wherein the substantiallylinear olefin polymer is a copolymer of ethylene and 1-hexene.
 27. Thecomposition of claim 7, wherein the substantially linear olefin polymeris a copolymer of ethylene and 1-butene.
 28. The composition of claim 7,wherein the substantially linear olefin polymer is a copolymer ofethylene and 4-methyl-1-pentene.
 29. The substantially linear olefinpolymer of claim 13, wherein the polymer is a copolymer of ethylene and1-octene.
 30. The substantially linear olefin polymer of claim 13,wherein the polymer is a copolymer of ethylene and 1-hexene.
 31. Thesubstantially linear olefin polymer of claim 13, wherein the polymer isa copolymer of ethylene and 1-butene.
 32. The substantially linearolefin polymer of claim 13, wherein the polymer is a copolymer ofethylene and 4-methyl-1-pentene.
 33. The substantially linear olefinpolymer of claim 17, wherein the polymer is a copolymer of ethylene and1-octene.
 34. The substantially linear olefin polymer of claim 17,wherein the polymer is a copolymer of ethylene and 1-hexene.
 35. Thesubstantially linear olefin polymer of claim 17, wherein the polymer isa copolymer of ethylene and 1-butene.
 36. The substantially linearolefin polymer of claim 17, wherein the polymer is a copolymer ofethylene and 4-methyl-1-pentene.
 37. A composition comprising:(i) asubstantially linear olefin polymer, wherein the substantially linearolefin polymer is characterized as having:a) from about 0.01 to about 3long chain branches/1000 carbons along the polymer backbone and b) acritical shear stress at onset of gross melt fracture of greater thanabout 4×10⁶ dyne/cm², and (ii) at least one other natural or syntheticpolymer, wherein the substantially linear olefin polymer is furthercharacterized as a copolymer of ethylene with a C₃ -C₂₀ alpha-olefin.38. The substantially linear olefin polymer of claim 12 wherein (a) isan amidosilane- or amidoalkanediyl- compound corresponding to theformula: ##STR8## wherein: M is titanium, zirconium or hafnium, bound inan η⁵ bonding mode to the cyclopentadienyl group;R' each occurrence isindependently selected from the group consisting of hydrogen, silyl,alkyl, aryl and combinations thereof having up to 10 carbon or siliconatoms; E is silicon or carbon; X independently each occurrence ishydride, halo, alkyl, or aryl, of up to 20 carbons; and m is 1 or 2.